Refractory lining in a vertical shaft furnace

ABSTRACT

A multipart refractory assembly comprising a left hand section comprised of two mated parts and a right hand section comprised of two mated parts, which sections when laid-up contiguously form a portion of the bustle of a vertical shaft furnace and an inlet passage extending from the bustle to the interior of the vertical shaft furnace. The left hand section is made of two refractory shapes which are placed one atop the other and are locked in place by tongue and groove means. The upper part has six faces. Five of the faces are plane surfaces. The bottom face is provided with a tongue in the rear portion thereof, a groove in the forward portion thereof and a curvilinear portion connecting the rear portion and the forward portion. The lower part also has six faces. Five of the faces are plane surfaces. The upper face is provided with a tongue in the forward portion thereof, a groove in the rear portion thereof and a curvilinear surface connecting the forward portion and rear portion. A side face of the lower part is provided with a groove extending from the curvilinear surface to the forward face thereof. When the bottom face of the upper part and the top face of the lower part are placed together the tongue and groove in the upper part mate with the groove and tongue in the lower part to lock the parts together. The curvilinear surfaces in the parts form a continuous surface which is generally elliptical in shape. The right hand section is a mirror image of the left hand section. When the left hand and right hand sections are laid-up contiguously, the generally semi-circular grooves in the side faces form a generally circular inlet passage extending from the generally elliptical surface of the forward face of the assembly. A generally elliptical opening or port is formed in the front face of the assembly. The upper parts of each section are identical. Therefore by mating two upper parts a section which does not contain an inlet passage or a port can be formed. Laying two sections of these parts contiguously forms a four-piece refractory assembly which does not have an inlet passage extending from the elliptical surface to a front face of the refractory assembly. The use of the two four-piece refractory assemblies described above in laying-up the refractory lining of a vertical shaft furnace makes it possible to assure uniform distribution of hot combustion gases into a pellet bed in the vertical shaft furnace to thereby distribute heat uniformly into the pellet bed.

United States Patent [191 Dominguez et al.

[451 Aug. 20, 1974 1 1 REFRACTORY LINING IN A VERTICAL SHAFT FURNACE[75] Inventors: Ezekiel C. Dominguez, Bethlehem;

John D. Lynn, Center Valley; George J. Sundy, Bethlehem, all of Pa.

[73] Assignee: Bethlehem Steel Corporation,

Bethlehem, Pa.

22 Filed: Feb. 7, 1973 211 Appl. No.: 330,340

Primary Examiner-Gerald A. Dost Attorney, Agent, or Firm-Joseph J.OKeefe; Charles A. Wilkinson; John S. Simitz [57] ABSTRACT A multipartrefractory assembly comprising a left hand section comprised of twomated parts and a right hand section comprised of two mated parts, whichsections when laid-up contiguously form a portion of the bustle of avertical shaft furnace and an inlet passage extending from the bustle tothe interior of the vertical shaft furnace. The left hand section ismade of two refractory shapes which are placed one atop the other andare locked in place by tongue and groove means. The upper part has sixfaces. Five of the faces are plane surfaces. The bottom face is providedwith a tongue in the rear portion thereof, a groove in the forwardportion thereof and a curvilinear portion connecting the rear portionand the forward portion. The lower part also has six faces. Five of thefaces are plane surfaces. The upper face is provided with a tongue inthe forward portion thereof, a groove in the rear portion thereof and acurvilinear surface connecting the forward portion and rear portion. Aside face of the lower part is provided with a groove extending from thecurvilinear surface to the forward face thereof. When the bottom face ofthe upper part and the top face of the lower part are placed togetherthe tongue and groove in the upper part mate with the groove and tonguein the lower part to lock the parts together. The curvilinear surfacesin the parts form a continuous surface which is generally elliptical inshape.

The right hand section is a mirror image of the left hand section. Whenthe left hand and right hand sections are laid-up contiguously, thegenerally semi-circular grooves in the side faces form a generallycircular inlet passage extending from the generally elliptical surfaceof the forward face of the assembly. A generally elliptical opening orport is formed in the front face of the assembly.

The upper parts of each section are identical. Therefore by mating twoupper parts a section which does not contain an inlet passage or a portcan be formed. Laying two sections of these parts contiguously forms afour-piece refractory assembly which does not have an inlet passageextending from the elliptical surface to a front face of the refractoryassembly. The use of the two four-piece refractory assemblies describedabove in laying-up the refractory lining of a vertical shaft furnacemakes it possible to assure uniform distribution of hot combustion gasesinto a pellet bed in the vertical shaft furnace to thereby distributeheat uniformly into the pellet bed.

10 Claims, 6 Drawing Figures I REFRACTORY LINING IN A VERTICAL SHAFTFURNACE BACKGROUND OF THE INVENTION This invention is directed tovertical shaft type furnaces lined with refractory shapes and moreparticularly to a refractory assembly formed by laying-up a plurality ofrefractory shapes contiguously to form a portion of the bustle and aninlet passage and an attendant port in the refractory lining in theupper stove of a vertical shaft furnace whereby hot combustion gases areintroduced into the upper stove of the furnace.

Balled iron ores and/or concentrates are frequently heated in a verticalshaft furnace to elevatedtemperatures and are thereby heat hardened toform pellets which are suitable for charging into metallurgicalfurnaces, such as blast furnaces, electric furnaces and the like. Theballed iron ores and/or concentrates are charged into the top section,called the upper stove, of the vertical shaft furnace. Hot combustiongases generated in external combustion chambers are introduced into thelower portion of the upper stove and pass upwardly through the ballediron ores and/or'concentrates to thereby heat the balls to a temperaturesufficiently high to harden the balls and form pellets therefrom. Thepellets move downwardly to a lower stove of the vertical shaft furnacewhere the pellets are partially cooled by atmospheric air passingupwardly through the vertical shaft furnace. The amount of air drawninto the lower stove and passing upwardly through the pellets is suchthat the air is heated to a temperature about equal to the temperatureof the hot combustion gases. The partially cooled pellets pass out ofthe vertical shaft furnace to a separate cooler where additionalatmospheric air is blown upwardly through the pellets, which are therebycooled to a temperature sufficiently low to allow handling on beltconveyors. The heat absorbed by the cooling air is transferred through aheat exchanger to fresh atmospheric air which is preheated and fed intothe external combustion chambers. Fuel oil or natural gas is burned inthe external combustion chambers to generate the hot combustion gaseswhich are introduced into the upper stove to harden the balled iron oresand/or concentrates. The hot combustion gases pass from the externalcombustion chambers through a refractory lined flue which connects theexternal combustion chambers to the vertical shaft furnace, to thebustle of the vertical shaft furnace. A series of spaced inlet passagesand ports, which extend from the bustle to the lower portion of theupper stove of the vertical shaft furnace, are provided to introduce thehot combustion gases into the lower portion of the upper stove of thevertical shaft furnace. The hot combustion gases pass upwardly throughthe balled iron ores and/or concentrates to heat the balls totemperatures of 2,100 to 2,500 F. to harden the balls and form pellets.

The bustle of the vertical shaft furnace is formed in the refractorylining of the vertical shaft furnace and generally comprises a passageformed by the refractory shapes in the refractory lining. The inletpassages and attendant ports through which the hot combustion gases areintroduced into the upper stove of the vertical shaft furnace are formedeither in the refractory shapes used to lay-up the refractory lining orare formed by spaces left between the refractory shapes when layingupthe refractory lining.

Unfortunately, the refractory lining is conventionally laid-up in thevertical shaft furnace in a manner such that the bustle is locatedoutside or beyond the outer vertical refractory wall of the verticalshaft furnace. Consequently, when the refractory lining which forms thebustle is heated during furnace operation, the refractory lining expandsupwardly creating a shear plane in line with the steel shell of thevertical shaft furnace. The refractory shapes which form the top of thebustle tend to crack at or near the center of the span because of theshear forces produced by the thermal expansion. The refractory shapes inthe refractory lining above the bustle also tend to crack or separatefrom each other. These refractory shapes become loose and are tiltedtoward the interior of the vertical shaft furnace because of thepressure exerted upon the inside face of the tile by the heatedcombustion gases.

The hot combustion gases are fed under pressure into the furnace. Anycracks in the refractory lining allow leakage of the gases from thebustle into the interior of the vertical shaft furnace without passingthrough the spaced inlet passages and attendant ports, thereby upsettingthe distribution of the hot' combustion gases passing through the inletpassages into the vertical shaft furnace and resulting in a non-uniformdistribution of the hot combustion gases in the bed of balled iron oresand/or concentrates in the vertical furnace. As a consequence,non-uniform heating of the balled iron ores and/or concentrates occurs.Increasing the pressure of the hot combustion gases in the bustle in anattempt to correct the non-uniform heating problem actually aggravatesthe situation and causes further excessive gas leakage. The increasedpressure of the hot combustion gases causes the loose and the crackedrefractory shapes forming the bustle to tilt inwardly into the verticalshaft furnace. The tilt of the refractory shapes often becomes quitesevere. Pellets also collect around the attendant ports of the inletpassages, resulting in the fusing of the pellets and clogging of theports and inlet passages.

The vertical shaft furnace must frequently be taken out of production torepair the refractory lining. As a result, loss of production time isexcessive. If the refractory lining is not repaired the back-pressurefrom the hot combustion gases needed for pelletizing the balled ironores and/or concentrates causes the bustle area to be pushedout-of-alignment, further increasing the cracking problem. If thepressure of the incoming hot combustion gases is reduced to alleviatethe cracking problem, non-uniform heating of the pellets also occurs,thereby causing variations in pellet quality and reduced productionbecause of inefficient and ineffective heating of the balled iron oreand/or concentrates in the upper stove.

It is therefore an object of this invention to provide a bustle andattendant inlet passages and ports whereby problems related to thermicexpansion are eliminated.

It is a further object of this invention to provide a refractoryassembly comprising a portion of the bustle and attendant inlet passagesand ports for a vertical shaft furnace which will allow the use ofhigher back pressures to introduce hot combustion gases required forpelletization into the shaft of the furnace.

It is another object of this invention to provide a refractory assemblycomprising a portion of the bustle and attendant inlet passages andports which will result SUMMARY OF THE INVENTION The improvedconstruction of the refractory lining of I a vertical shaft furnaceaccording to the present invention includes the use of a plurality ofnovel refractory assemblies in the bustle and inlet passage area of therefractory lining. The novel refractory assembly includes a plurality ofrefractory shapes which form a portion of the bustle and vertical wallin the upper stove of the shaft furnace. An inlet passage extending fromthe bustle to the interior of the vertical shaft furnace and culminatingin a port is incorporated into the assembly. The inlet passage isinclined downwardly at an angle from the bustle to a plane parallel tothe base of the assembly.

DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional end view ofprior art bustle and attendant inlet passages and ports in a verticalshaft furnace.

FIG. 2 is a cross-sectional end view of the improved refractory liningof the invention in which a plurality of the refractory assemblies areincorporated in the refractory lining.

FIG. 3 is an isometric view of the refractory assembly of the invention.

FIG. 4 is an exploded isometric view of the preferred quadripartiterefractory assembly of the invention.

FIG. 5 is an isometric view of a variation of the refractory assembly ofthe invention.

FIG. 6 is an exploded isometric view of one variation of the bustle andinlet passage refractory assembly of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the figures, FIG. 1is a cross-sectional view of the end wall of a prior art vertical shaftpelletizing furnace including an upper stove and a lower stove, showingthe conventional method of incorporating a bustle, attendant inletpassages and ports in the refractory lining at the bottom of the upperstove of the vertical shaft furnace. The vertical shaft pelletizingfurnace, shown generally at 10, comprisesa steel shell 11 and arefractory liningv 12, comprising various refractory shapes laid-upinside the steel shell 11. The refractory shapes are usually made fromalumina and aluminasilica raw materials. The refractory lining I2 islaid-up to form a generally rectangular space or opening 13, called abustle, which extends around the four sides of the vertical shaftfurnace. A refractory cover tile 19 forms the top of the bustle 13. Arefractory port tile 14 forms the front wall 14a of the bustle 13. Theback wall 14b and bottom 14c of the bustle 13 are formed by therefractory shapes laid-up to form the refractory lining 12 of thevertical shaft furnace 10. An inlet passage 15 is provided in therefractory port tile 14 to allow hot combustion gases, which arerequired to harden the balled iron ores and/or concentrates to therebyform pellets, to pass from the bustle 13 into the interior 16 of thevertical shaft furnace 10. The inlet passage 15 is directedsubstantially diagonally downwardly from the front wall 14a of thebustle 13 to the interior 16 of the vertical shaft furnace 10. Thedownwardly directed position of the opening 15a of the inlet passage 15prevents ingress of the hot pellets into the inlet passage 15 andprevents clogging of the port 15a.

A straight line projection (dotted line) of the steel shell 11 of thevertical shaft furnace 10 from the upper portion 17 thereof to the lowerportion 18 thereof, passes along the front wall of the bustle 13. Whenthe refractory shapes which form the refractory lining 12 in the lowerportion 18 of the vertical shaft furnace l0 become heated by hotcombustion gases they expand upwardly causing a shear plane to formalong the straight line projection of the steel shell 11. The shearstresses created in the refractory lining cause the refractory covertile 19 to crack at the point of maximum stress which is at or near thecenter of the refractory cover tile 19. The refractory cover tile 19also supports a portion of the refractory lining in the upper stove ofthe vertical shaft furnace. When the refractory cover tile 19 cracks,the support is weakened thereby allowing the refractory shapes whichform the refractory lining to shift. The refractory shapes can crack orcan part along the line 19a19b. The cracked portion of the refractorylining has a tendency to move toward the interior 16 of the verticalshaft furnace 10. The portion 19c of the refractory lining 12 isliterally pushed into the vertical shaft furnace 10 by the pressure ofthe hot combustion gases in the bustle. The back-pressure of the hotcombustion gases in the bustle decreases because of leakage through thecracks l9a-19b in the refractory lining 12, resulting in nonuniformdistribution of the hot combustion gases into the bed of balled iron oreand/or concentrates in the vertical shaft furnace 10. The overalluniform quality of the pellets formed under such conditions is poor.Increasing the back pressure of the hot combustion gases in the bustle13 of the vertical shaft furnace 10 results in tilting the crackedportion 190 of the refractory lining l2 farther into the interior 16 ofthe vertical shaft furnace 10 and does not improve the non-uniform flowof the hot combustion gases into the pellet bed. Hence, improvement inthe uniform quality of the pellets is not achieved even at aconsiderable increase in fuel consumption.

Theimproved construction of the bustle and inlet passage and attendantport in the refractory lining of a vertical shaft furnace in accordancewith the present invention is shown in FIG. 2. To properly compare theimproved construction of the invention with prior art construction,identical numbers as used in FIG. I to identify the parts of thevertical shaft furnace will also be used to identify corresponding oridentical parts in FIG. 2.

The refractory lining l2 laid-up against the steel shell 11 of thevertical shaft furnace 10 includes a refractory assembly 14 of matedrefractory shapes 14d and Me which are laid-up contiguously in therefractory lining 12. The assembly 14 forms a portion of the generallyelliptical bustle 13 and includes a generally cylindrical inlet passage15. Note that the inlet passage 15 extends generally verticallydownwardly from the bustle 13 toward the base of the refractory assemblyas it extends toward the interior 16 of the vertical shaft furnace 10.The generally elliptical port a of the inlet passage 15 is in line withthe inside surface 12a of the refractory lining 12, unlike the port 15aof the inlet passage 15 in the prior art construction. It has been foundthat the pellets in the pellet bed do not collect nor intrude into theinlet passage 15 through the port 15a of the improved construction ofthe invention to thereby block the port 15a whereas the prior artconstruction was susceptible to blockage of the port 15a because ofpellet buildup along the inclined portion 12b of the surface 12a of therefractory lining 12. With the new construction of the bustle and inletpassage assembly 14, no cantilever loading is included in the refractorylining 12. In the improved construction, a shear plane is deliberatelybuilt into the refractory lining to relieve the shear stresses caused bythe thermal expansion of the refractory shapes. The thermal expansion ofthe refractory shapes which form the refractory lining is distributedmore evenly and transmitted more evenly through the bustle and inletpassage assembly, thereby eliminating the problem of cracking andseparation of refractory shapes which form the refractory lining abovethe bustle and inlet passage area of the refractory lining as in theprior art. Although we have shown a row of the refractory assemblies 14extending across one end wall of the vertical shaft furnace, several ofthe refractory assemblies can be made in a manner to exclude the inletpassage 15 and port 15a. While we have used the refractory assembliesonly in the long walls of the vertical shaft furnace, the refractoryassemblies can be used in both the end walls and the long walls of thevertical shaft furnace to provide equal distribution of hot combustiongases within the upper stove of the vertical shaft furnace. The row ofrefractory assemblies can contain one or any number of inlet passages 15and ports 15a which are desired or required to produce uniform heatingof the balled iron ores and/or concentrates to produce a uniform qualityof pellets.

The preferred embodiment of the refractory bustle and inlet passageassembly of the invention is a quadripartite assembly as shown inisometric view, FIG. 3, and exploded isometric view, FIG. 4.

Turning now to FIG. 3, the quadripartite refractory assembly 14 is madeof two pairs of mated refractory shapes comprising a left hand sectionformed by mated upper part 21 and lower part 22 and a'right hand section23 formed by mated upper part 24 and lower part 25. The left handsection 20 and right hand section 23 are laid-up contiguously in therefractory lining and are opposite hands, or mirror-images, of eachother. A generally oval or elliptical opening 13a, which forms a portionof the bustle 13, is formed when the parts 21, 22, 24 and 25 areassembled as shown. A generally cylindrical inlet passage 15 is formedby the lower parts 22 and 25 in the manner shown. The inlet passage 15extends generally diagonally outwardly and downwardly from the bustle 13to a generally elliptical port 15a, which is the external opening of theinlet passage 15. The parts 21, 22, 24 and 25 are held in place bytongues 26 and 27 which fit into grooves 28 and 29 respectively as shownin FIG. 3. The assembly 14 in FIG. 3 is shown with the parts in spacedrelationship to each other for clarity only. In actual use the upper andlower parts are mated to form the left hand section and the right handsection which in turn are laid-up contiguously or butted together toform the refractory assembly 14.

Turning now to the exploded isometric view, FIG. 4, the left handsection 20, comprising upper part 21 and lower part 22, and the righthand section 23, comprising upper part 24 and lower part 25, areopposite hand of each other, therefore only the left hand section 20will be described. It will be noted that upper parts 21 and 24 areidentical and can be substituted for each other in forming therefractory assembly. All the refractory shapes in the refractoryassembly 14 have six faces. Five of the faces are plane surfaces whilethe sixth face comprises two plane surfaces and a curvilinear surface.The left hand section 20 comprises two mated parts, an upper part 21 anda lower part 22. The upper part 21 is generally a parallelepiped and hasgenerally rectangular parallel front and rear faces 37 and 38respectively and generally rectangular parallel sides 39 and 40. (Rearface 38 and side are not shown.) The bottom face 31 comprises a flatgenerally rectangular front portion 32, a flat generally rectangularrear portion 33 in spaced relationship to the forward portion 32 and acurvilinear portion 34, which is one-half of a generally ellipticalsurface, extending from the rear edge 35 of the forward portion 32 tothe forward edge 36 of the rear portion 33. The forward portion 32 ofthe bottom face 31 is provided with a generally semicircular groove 29extending from the side 39 to the side 40 and parallel to the face 37.While we have shown the groove 29 as being semi-circular, the groove 29can be other shapes, for example, rectangular, triangular, orcurvilinear and can be placed anywhere between the face 37 and rear edge35 on the forward portion 32 but it is preferred to make the groovesemicircular and to position the groove 29 midway between the face 37and the rear edge 35 of the forward portion 32. The rear portion 33 ofthe bottom face 31 is provided with a semi-circular tongue 26 extendingfrom the side 39 to the side 40. The tongue 26 is parallel to the face38 and the front edge 36 of the rear portion 33. The tongue 26 can alsobe other shapes, for example, rectangular, triangular, or curvilinearand can be formed anywhere between the forward edge 36 and face 38 onthe rear portion 33, but it is preferred to make the tongue semicircularin shape and to place the tongue 26 about midway between the face 38 andthe front edge 36 of the rear portion 33.

The lower. part 22 is generally a parallelepiped and has generallyrectangular parallel end faces which can be designated as front and rearfaces 51 and 51a respectively and generally rectangular parallel sidefaces 49 and 50 (rear face 51a and side face 50 are not shown), and aflat generally rectangular bottom face 42 parallel to a top face 43. Thetop face 43 has a flat generally rectangular forward portion 44, a flatgenerally rectangular rear portion 45 in spaced relationship with theforward portion 44 and a curvilinear portion 46 which is generallyelliptical in shape, extending from the rear edge 47 of the forwardportion 44 to the forward edge 48 of the rear portion 45. The forwardportion 44 of the top face 43 is provided with tongue 27 having the sameshape as the groove 29 in the upper part 21 and is positioned on theforward portion 44 so as to mate with the groove 29 on the forwardportion 32 of the upper part 21 when the upper part 21 and lower part 22are fitted together. The rear portion 45 is provided with a groove 28.The groove 28 has the same shape as the tongue 26 and is positioned onthe rear portion 45 so that it will mate with the tongue 26 when theupper part 21 and the lower part 22 are joined together as shown. Wehave shown the groove 29 formed in the forward portion 32 and the tongue26 formed in the rear portion 33 of the bottom face 31 of the upper part21 but the groove 29 and the tongue 26 can be interchanged, that is, thegroove 29 can be incorporated in the rear portion 33 and the tongue 26can be incorporated in the forward portion 32. Of course, if theposition of the groove 29 and the tongue 26 re reversed as suggestedabove, then the positions of tongue 27 and groove 28 in the forwardportion 44 and rear portion 45 respectively in the top face 43 of thelower part 22 are so reversed so that when the bottom face 31 of theupper part 21 and the top face 43 of the lower part 22 are laid-upcontiguously, the groove 29 and the tongue 26 will mate as will thegroove 28 and the tongue 27 to thereby interlock the upper part 21 andthe lower part 22. Of course, this reversal of groove and tongue canalso be applied to the upper part 24 and lower part 25 of the right handsection 23. It can, therefore, be seen that the positions of the tonguesand grooves are immaterial so long as they have the same geometricconfiguration and cooperate to form a tongue and groove interlockingarrangement.

One of the parallel sides 49 is provided with a grooved passage 52 whichis shown as generally semicylindrical in shape. The grooved passage 52extends from the upper part of the curvilinear portion 46 diagonallydownwardly to one of the end faces 51 which can be designated as thefront face of the lower part 22 and forms a generally semi-ellipticalopening a in the front face 51.. When the left hand section and theright hand section 23 are laid-up contiguously or butted together, agenerally cylindrical passage 15 is formed by the grooved passage 52extending from the bustle 13 to the front face 51. The passage 15 isformed so that if either an extension 54a of the axis of the passage 15or a diagonal line 54 is drawn parallel to the side of passage 15 itwill pass through a plane 42a which is an extension of the bottomsurface 42 making an angle 4) therewith. The angle (i) should not bemore than 89 and not less than 46. It is preferred that the angle 100 benot more than 89 and not less than about 80. The groove 52 can be of anycurvilinear surface such as oval, elliptical and-the like or can besquare or rectangular and the like. Of course, the port 15a will changein shape consistent with the shape of groove 52.

While the quadripartite bustle and inlet passage refractory assembly hasbeen shown and described, it must be understood that variations ofconstruction can be used, as shown in FIG. 6. Note that in FIG. 6 theinlet passage 15 extends downwardly to the bottom 42 of the side 49. Aventuri 53 is shown in the passage 52 to minimize the pressure drop ofthe hot combustion gases passing through passage 52 into the verticalshaft furnace. The inlet passage 52 can be made without the inclusion ofthe venturi 53. It does not matter which refractory assembly is used aslong as the angle 4) is not more than 89 and not less than 46 and theinlet passage 15 is continuous from the bustle 13 to the front face ofthe refractory assembly.

While we have shown the integral bustle and inlet passage assembly ofthe invention as a four piece assembly, it will be understood that therefractory assembly could be made in one piece, two pieces or threepieces; for example, the top pieces 39 and 24 can be made as onerefractory shape, or the bottom pieces 49 and can be made as one piece,thereby resulting in three piece assemblies. If the top pieces 39 and 24are made as one refractory shape and the bottom pieces 49 and 25 aremade as one refractory shape, or if the left hand section 20 is made asone refractory shape and the right hand section 23 is made as onerefractory shape, then two piece assemblies will result. Of course, theentire assembly could be made in one piece. However, weight, ease ofhandling in shipping and installation, ease of manufacture, thermalexpansion problems and economic considerations will dictate whichvariations should be used. We prefer either of the quadripartiteassemblies shown in FIGS. 3, 4 and 5.

In constructing the upper portion of the refractory lining in thevertical shaft furnace which contains the bustle and inlet passages, itmust be recognized that the inlet passages are spaced equidistant apartalong the long walls and end walls of the vertical shaft furnace toinsure a uniform distribution of hot combustion gases into the pelletbed.

Since the upper left hand section 21 and upper right hand section 24 areidentical, the bustle 13 per se can be formed merely by fitting togetherfour parts similar to either part 21 or part 24. Thus, when it isdesired to form an assembly 14 without an inlet passage 15, the lowerleft hand section 22 and lower right hand section 25 are not used.Instead, either parts 21 or 24 are substituted for the parts 22 and 25.

As an example of our invention, the hustle and inlet passage refractoryassembly as shown in FIG. 5 was installed as part of the refractorylining in the end wall of a vertical shaft furnace. The total aggregateport area, that is, the area through which hot combustion gases areintroduced around the vertical shaft furnace, was reduced from 234square inches-using the prior art method of forming a bustle and inletpassage arrangement in FIG. 1, to l4l square inches using the bustle andinlet passage refractory assembly of the invention as shown in FIG. 5.After a period of five months operation there was no deterioration ormovement of the refractory lining surrounding the bustle and inletpassage refractory assembly. Scale build-up on the vertical shaftfurnace wall was minimal. Pellet bed temperature was maintained uniformbetween 2,300 F. and 2,400 F. The pellet quality was as good as, if notbetter than, pellet quality obtained when using standard bustle andinlet passage construction. Temperature tests wherein nichrome wire testbrackets containing a temperature indicator and travelling thermocoupleswere passed downwardly through the pellet bed showed that no cold spotsoccurred in the pellet bed and temperature remained constant with arange of about'2,300 F. to 2,400 F.

We claim:

1. A bustle and inlet passage refractory assembly comprising a left handsection and a right hand section, each of said sections being dividedinto two mating parts, an upper part and a lower part, the upper part ofeach section having substantially parallel top and bottom faces,parallel front and rear end faces and parallel side faces, the bottomface comprising a forward portion and a rear portion in parallel spacedrelationship, said forward portion and said rear portion being joined bya first curvilinear section generally elliptical in shape, said forwardportion and rear portion being provided with interlocking and matingmeans; the lower part of each section having generally parallel top andbottom faces, generally parallel front and rear end faces and parallelside faces, said top face comprising a second forward portion and asecond rear portion in parallel spaced relationship, said second forwardportion and said second rear portion being joined by a secondcurvilinear section generally elliptical in. shape, said second forwardportion and second rear portion being provided with interlocking andmating means, whereby said top face of said lower part and said bottomface of said upper part are interlocked and mated to form one-half ofsaid refractory assembly, said first curvilinear surface and said secondcurvilinear surface forming a generally elliptical passage, a groovedpassage formed in one of said parallel side faces of said lower partextending substantially diagonally downwardly from the upper part of thesecond curvilinear section to the front face of the lower part andterminating in an opening in said front face, said opening being inspaced relationship with said bottom face of said lower part, saidgrooved passage being at an angle of not more than 89 and not less than46 with said bottom face of said lower part.

2. The bustle and inlet passage refractory assembly of claim 1 whereinthe interlocking and mating means comprise a first tongue formed on saidforward portion of the upper part extending from one parallel side faceto the other parallel side face and being generally parallel to the endfaces, a first groove formed on said rear portion of the upper partextending from one parallel side face to the other parallel side faceand being generally parallel to the end faces, a second groove formed onsaid forward portion of the lower part having essentially the samegeometric configuration of the tongue formed in the forward portion ofthe upper part and extending from one parallel side face to the otherparallel side face and being generally parallel to the end faces, and asecond tongue formed on said rear portion of said lower part havingessentially the same geometric configuration of the groove formed in therear portion of said upper part and extending from one parallel sideface to the other parallel side face and being generally parallel to theend faces.

3. The refractory assembly of claim 2 wherein said first and secondtongues and said first and second grooves are semi-cylindrical inconfiguration.

4. The assembly according to claim 1 additionally comprising aconstriction in said grooved passage.

5. An improved refractory lining in a vertical shaft furnace having anupper stove and a lower stove, a steel shell and a refractory lininglaid-up inside the steel shell and wherein said refractory liningincludes a bustle and inlet passage section whereby hot combustion gasesare introduced into the interior of the upper stove of the verticalshaft furnace, said bustle and inlet passage section comprising aplurality of quadripartite refractory assemblies comprised of matedcontiguous refractory shapes defining between them portions of thebustle and a plurality of inlet passages in the refractory lining.

6. A multipartite refractory assembly for a vertical shaft furnacecomprising preformed mating refractory parts which form sections whichwhen laid-up contiguously define a bustle pipe having gas passagesextending diagonally downwardly from the bustle pipe to a port in asubstantially vertical internal wall of said furnace and intersecting asubstantially horizontal plane at an angle of from 46 to 89.

7. The assembly of claim 6 wherein the angle of intersection is from to89.

8. An improved refractory lining in a vertical shaft pelletizing furnacehaving an upper stove and a lower stove, a steel shell and a refractorylining laid up inside the steel shell and including a bustle and inletpassage area whereby hot combustion gases are introduced into theinterior of the upper stove of the vertical shaft pelletizing furnacecomprising:

a. a series of refractory shapes laid-up contiguously one upon anotherto form a refractory lining having a predetermined thickness and asubstantially even cylindrical inside surface in said vertical shaftpelletizing furnace,

b. a multipartite preformed bustle and inlet passage refractory assemblyhaving substantially the same predetermined width as the refractorylining of subparagraph (a) in the refractory lining of said verticalshaft pelletizing furnace and positioned intermediate an upper portionand a lower portion of the refractory lining with the interior face ofthe said refractory assembly substantially in-line with said upper andlower portions of the refractory lining,

c. said multipartite preformed bustle and inlet passage refractoryassembly comprising a series of contiguously laid interengagingsubstantially L- shaped oppositely disposed refractory shapes definingin the angles of the Us portions of a bustle passage extending aroundsaid vertical shaft pelletizing furnace and wherein the bottom and topof the assembly is composed of legs of the oppositely disposed L-shapedrefractory shapes, and

d. a downwardly inclined inlet passage passing from the bustle passageto the interior furnace face of said refractory assembly and defined bycoacting grooves in side faces of the arms of a plurality of the saidL-shaped refractory shapes of said refractory bustle assembly.

9. The improved refractory lining of claim 8 wherein the angle of thedownwardly inclined inlet passage intersects a substantially horizontalplane at an angle of from 46 to 89.

10. The improved refractory lining of claim 9 wherein the angleofintersection is 80 to 89.

1. A bustle and inlet passage refractory assembly comprising a left handsection and a right hand section, each of said sections being dividedinto two mating parts, an upper part and a lower part, the upper part ofeach section having substantially parallel top and bottom faces,parallel front and rear end faces and parallel side faces, the bottomface comprising a forward portion and a rear portion in parallel spacedrelationship, said forward portion and said rear portion being joined bya first curvilinear section generally elliptical in shape, said forwardportion and rear portion being provided with interlocking and matingmeans; the lower part of each section having generally parallel top andbottom faces, generally parallel front and rear end faces and parallelside faces, said top face comprising a second forward portion and asecond rear portion in parallel spaced relationship, said second forwardportion and said second rear portion being joined by a secondcurvilinear section generally elliptical in shape, said second forwardportion and second rear portion being provided with interlocking andmating means, whereby said top face of said lower part and said bottomface of said upper part are interlocked and mated to form onehalf ofsaid refractoRy assembly, said first curvilinear surface and said secondcurvilinear surface forming a generally elliptical passage, a groovedpassage formed in one of said parallel side faces of said lower partextending substantially diagonally downwardly from the upper part of thesecond curvilinear section to the front face of the lower part andterminating in an opening in said front face, said opening being inspaced relationship with said bottom face of said lower part, saidgrooved passage being at an angle of not more than 89* and not less than46* with said bottom face of said lower part.
 2. The bustle and inletpassage refractory assembly of claim 1 wherein the interlocking andmating means comprise a first tongue formed on said forward portion ofthe upper part extending from one parallel side face to the otherparallel side face and being generally parallel to the end faces, afirst groove formed on said rear portion of the upper part extendingfrom one parallel side face to the other parallel side face and beinggenerally parallel to the end faces, a second groove formed on saidforward portion of the lower part having essentially the same geometricconfiguration of the tongue formed in the forward portion of the upperpart and extending from one parallel side face to the other parallelside face and being generally parallel to the end faces, and a secondtongue formed on said rear portion of said lower part having essentiallythe same geometric configuration of the groove formed in the rearportion of said upper part and extending from one parallel side face tothe other parallel side face and being generally parallel to the endfaces.
 3. The refractory assembly of claim 2 wherein said first andsecond tongues and said first and second grooves are semi-cylindrical inconfiguration.
 4. The assembly according to claim 1 additionallycomprising a constriction in said grooved passage.
 5. An improvedrefractory lining in a vertical shaft furnace having an upper stove anda lower stove, a steel shell and a refractory lining laid-up inside thesteel shell and wherein said refractory lining includes a bustle andinlet passage section whereby hot combustion gases are introduced intothe interior of the upper stove of the vertical shaft furnace, saidbustle and inlet passage section comprising a plurality of quadripartiterefractory assemblies comprised of mated contiguous refractory shapesdefining between them portions of the bustle and a plurality of inletpassages in the refractory lining.
 6. A multipartite refractory assemblyfor a vertical shaft furnace comprising preformed mating refractoryparts which form sections which when laid-up contiguously define abustle pipe having gas passages extending diagonally downwardly from thebustle pipe to a port in a substantially vertical internal wall of saidfurnace and intersecting a substantially horizontal plane at an angle offrom 46* to 89*.
 7. The assembly of claim 6 wherein the angle ofintersection is from 80* to 89*.
 8. An improved refractory lining in avertical shaft pelletizing furnace having an upper stove and a lowerstove, a steel shell and a refractory lining laid up inside the steelshell and including a bustle and inlet passage area whereby hotcombustion gases are introduced into the interior of the upper stove ofthe vertical shaft pelletizing furnace comprising: a. a series ofrefractory shapes laid-up contiguously one upon another to form arefractory lining having a predetermined thickness and a substantiallyeven cylindrical inside surface in said vertical shaft pelletizingfurnace, b. a multipartite preformed bustle and inlet passage refractoryassembly having substantially the same predetermined width as therefractory lining of subparagraph (a) in the refractory lining of saidvertical shaft pelletizing furnace and positioned intermediate an upperportion and a lower portion of the refractory lining with the interiorface of the said refractory assembly substantially in-line with saidupper and lower portions of the refractory lining, c. said multipartitepreformed bustle and inlet passage refractory assembly comprising aseries of contiguously laid interengaging substantially L-shapedoppositely disposed refractory shapes defining in the angles of the L''sportions of a bustle passage extending around said vertical shaftpelletizing furnace and wherein the bottom and top of the assembly iscomposed of legs of the oppositely disposed L-shaped refractory shapes,and d. a downwardly inclined inlet passage passing from the bustlepassage to the interior furnace face of said refractory assembly anddefined by coacting grooves in side faces of the arms of a plurality ofthe said L-shaped refractory shapes of said refractory bustle assembly.9. The improved refractory lining of claim 8 wherein the angle of thedownwardly inclined inlet passage intersects a substantially horizontalplane at an angle of from 46* to 89*.
 10. The improved refractory liningof claim 9 wherein the angle of intersection is 80* to 89*.